Automatic whale detector keeps track of migrating whales

Gray whales make an annual trip from the Arctic where they feed in the summer down to Baja California for the winter. During this migration, scientists at NOAA use high-powered binoculars to manually count whales as they pass through a spot south of Monterrey Bay to get an idea of how the formerly-endangered population is doing.

Unfortunately, the scientists don't always get an accurate picture of how many whales there really are making this journey because they can't be looking through binoculars at all hours of the day and, when they are counting, it's easy to miss some or double-count others. A team at NOAA decided to come up with a better solution for studying the animals -- an automatic whale detector.

The system is made up of three infrared cameras that continually scan the water looking for the signs of whales, specifically the thermal marking of a whale surfacing to blow.

NOAA says, "The cameras themselves are nothing new—they’re similar to the infrared cameras that police use when searching for suspects from a helicopter. What is new is software that automatically analyzes the video to detect when a whale blows. To do that, it has to distinguish the blow of a whale from other signals that might confuse it, such as a bird diving into the water or a small boat passing by."

"A whale is this great big motor that takes in a breath of air and holds it inside for a long time," says Wayne Perryman, a NOAA Fisheries scientist. "When it exhales, the air is much warmer than the background, and we can detect that difference very easily, both day and night."

The computer is also able to keep track of individual whales so that it maintains an accurate count. It has an algorithm that predicts when whales will surface again based on whale diving behavior which enables it to keep track of each whale as it moves through the water.

The gray whale was once on the endangered species list after being hunted to very low numbers, but the species has made a great comeback and was removed from the list in 1994. The population is now at around 20,000, but scientists still monitor them because threats like ship strikes, fishing gear entanglement and climate change could all have major impacts on the species.

The new system will allow scientists to capture a much larger and more accurate sample size, which will let them see more clearly how things like loss of sea ice are affecting the animals.